LFN names without alloc

[uzytkownik]

The maximum name for LFN is 256 characters which is 512 bytes. This can be achievable on embedded systems if the hierarchy is not too deep.

Can LFN + !alloc be implemented as [u16; 256] instead of Vec<u16>? That would help on systems which don't have full memory allocator but still want to use LFN.

[aruiz]

Isn't this implemented already in dir.rs:744?